Embodiments of the invention relate generally to antennas. More particularly, embodiments of the invention relate to wideband antennas, including planar receiving antennas.
The gradual degradation of television (TV) video and audio signal quality seen in analog television systems often appears as xe2x80x9cghostingxe2x80x9d and other channel noise at the receiver. In a digital TV signal environment, multipath or low level signal conditions create bit errors that are initially seen as video artifacts, including blockiness and pixelization. There may also be audio artifacts. However, when the number of reception errors reaches a certain level, complete loss of the video image and accompanying audio can occur in a relatively abrupt manner.
One example of this situation arises when Digital TV/High Definition TV (DTV/HDTV) receivers have difficulty resolving multiple replicas of the same signal arriving at the receiver input (i.e., multipath signals). Replicated signals can effectively cancel out the data contained in the strongest direct path signal, which serves to increase the digital signal Bit Error Rate (BER) to the point where there are simply too many errors to display a coherent video image, or even to reproduce the audio portion of the signal. This effect, wherein a DTV broadcast is lost completely due to the existence of multipath or low level signals, has been labeled the xe2x80x9ccliff effectxe2x80x9d.
TV receivers generally rely on antennas to provide some relief from such problems. However, many TV antennas do not operate well under multipath signal conditions. Antennas that are more effective in dealing with multipath signals often have a limited response bandwidth, and some are characterized by a large wind area, creating a xe2x80x9csailxe2x80x9d which is easily damaged in moderate to high winds. For these and other reasons, antennas with the ability to reduce the negative effects of multipath signals, while offering a wider bandwidth and resistance to wind effects, are needed.
Embodiments of the invention described herein may be used to provide a wideband, planar receiving antenna that performs well under multipath signal reception conditions. An enhanced method of coupling signal energy to the antenna is utilized, and some of the structural elements may include an open mesh which operates to reduce the wind effects presented by outdoor installations.
In one embodiment, an energy feed structure may include two tubes, the first having an open end and a closed end, and the second located so as to pierce the closed end of the first tube. The feed structure includes a solid dielectric material to cover the open end of the first tube. The centerlines of the tubes are generally located so as to be offset, but substantially parallel.
In another embodiment, an apparatus may include a resonant element, a ground plane, and the energy feed structure (capacitively coupled to the resonant element), as described. Either, or both the resonant element and the ground plane may comprise a solid sheet of material, or an open mesh to reduce the wind effects of outdoor installations. The resonant element and the ground plane are typically separated using one or more non-conductive standoff elements.
In another embodiment, a system may include the apparatus described, as well as a radio frequency connector, wherein the feed structure is electrically coupled to the radio frequency connector. A support can be electrically coupled to the ground plane, and a cable may be electrically coupled to the radio frequency connector.
Thus, in yet another embodiment, a method of fabricating an apparatus and a system according to various embodiments of the invention may include forming a ground plane, forming a planar resonant element, and then forming an energy feed structure having a solid dielectric element.